Heating in Great Britain: An incumbent discourse coalition resists an electrifying future

•Incumbents in the UK heat sector are under threat from the potential of heat electrification associated with decarbonisation.•Critical discourse approaches are used to consider a storyline presented by incumbent actors in the UK heat sector.•Regime actors in the UK are promoting a vision for low carbon heat based around 'green' and low carbon gas.•Cost, sustainability and technical characteristics of low carbon gas are deeply uncertain despite being presented otherwise.•Policy should aim to reduce uncertainty while deploying known low carbon energy efficiency and electrification technologies.